US11286189B2 - Treatment of fluoride-containing wastewater - Google Patents
Treatment of fluoride-containing wastewater Download PDFInfo
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- US11286189B2 US11286189B2 US16/770,901 US201816770901A US11286189B2 US 11286189 B2 US11286189 B2 US 11286189B2 US 201816770901 A US201816770901 A US 201816770901A US 11286189 B2 US11286189 B2 US 11286189B2
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
- C02F1/583—Treatment of water, waste water, or sewage by removing specified dissolved compounds by removing fluoride or fluorine compounds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/145—Ultrafiltration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/147—Microfiltration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/16—Feed pretreatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/02—Inorganic material
- B01D71/021—Carbon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/02—Inorganic material
- B01D71/024—Oxides
- B01D71/025—Aluminium oxide
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
- C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2311/00—Details relating to membrane separation process operations and control
- B01D2311/04—Specific process operations in the feed stream; Feed pretreatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2311/00—Details relating to membrane separation process operations and control
- B01D2311/12—Addition of chemical agents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2311/00—Details relating to membrane separation process operations and control
- B01D2311/18—Details relating to membrane separation process operations and control pH control
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2311/00—Details relating to membrane separation process operations and control
- B01D2311/26—Further operations combined with membrane separation processes
- B01D2311/2642—Aggregation, sedimentation, flocculation, precipitation or coagulation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/24—Stationary reactors without moving elements inside
- B01J2219/2401—Reactors comprising multiple separate flow channels
- B01J2219/245—Plate-type reactors
- B01J2219/2475—Separation means, e.g. membranes inside the reactor
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/19—Fluorine; Hydrogen fluoride
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/105—Phosphorus compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
- C02F2101/14—Fluorine or fluorine-containing compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
- C02F2103/346—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from semiconductor processing, e.g. waste water from polishing of wafers
Definitions
- This invention relates to a method for treating fluoride-containing, in particular hydrofluoric acid (HF) containing wastewater to remove fluoride, and to a corresponding apparatus.
- fluoride-containing, in particular hydrofluoric acid (HF) containing wastewater to remove fluoride
- Fluoride is used to a very high extent in industry, especially in the semiconductor and nanotechnology industries as an etchant for different materials, e.g. for glass and silica.
- the most common source of fluoride is HF.
- buffered HF (BHF) containing e.g. ammonium bifluoride is used.
- fluoride reduction via alumina or ion exchange As higher doses of free fluorides can be harmful to humans and other lifeforms, it is essential to remove fluoride from industrial wastewater streams. Many different methods are known in this context, e.g. fluoride reduction via alumina or ion exchange.
- CaF 2 calcium fluoride
- calcite method granules of limestone
- calcium aqueous agents such as hydrated lime and calcium chloride solution in HF wastewater treatment
- the invention provides a method for treating fluoride-containing, in particular HF-containing wastewater to remove fluoride with the features of claim 1 .
- An apparatus suitable for this treatment is claimed in claim 10 .
- Preferred embodiments of the inventive method and of the inventive apparatus are defined in the claims dependent from claim 1 and dependent from claim 10 , respectively. The wording of all claims is hereby explicitly incorporated into this description by reference.
- calcium carbonate is reacted in a reaction step at an acidic pH ⁇ 4 with the fluoride, in particular the hydrofluoric acid in the wastewater to form calcium fluoride particles. Then, in a subsequent step said calcium fluoride particles are separated by filtration via a porous membrane from the treated wastewater.
- wastewater shall mean any water-based liquid which has to be cleaned or recycled.
- membrane shall include any synthetic membrane which is intended for separation purposes in laboratory or in industry. Those membranes are used to selectively retain substances, and to let pass other substances.
- Synthetic membranes can be made from a large number of different materials. They can be produced from organic materials, in particular from polymers. Membranes made from inorganic materials are often ceramic membranes, produced from inorganic materials such as aluminium oxides, zirconium dioxides or silicon carbide. Those ceramic membranes normally are stable against aggressive chemicals, like acids or certain solvents. Further they are thermally and mechanically stable, and normally biologically inert.
- the membranes used according to the invention are porous, wherein the degree of selectivity of the membrane depends on the pore size. Depending on this pore size, the membranes can be classified as microfiltration membranes, ultrafiltration membranes or nanofiltration membranes. Normally, according to the invention, flat and comparably thin membranes are used.
- cutoff shall describe the pore size of the membrane and it reflects to the maximum pore size distribution. With a pore size greater than 0.1 ⁇ m (and lower than 10 ⁇ m) globular molecules greater than 5000 kDa are retained by the membrane to 90%. This pore size range is the typical scope of microfiltration.
- calcium carbonate particles act as a seed material on which the calcium fluoride particles grow.
- the reaction step and the corresponding growth of the calcium fluoride particles not only calcium carbonate of the reaction solution, but also calcium carbonate in the core of the growing particles is consumed. This results in a considerable number of comparably big particles of calcium fluoride, mostly with a remaining calcium carbonate core.
- reaction solution also present in the reaction solution are small particles of calcium fluoride which mainly do not result from a reaction on calcium carbonate seed particles.
- Both the bigger calcium fluoride particles and the smaller calcium fluoride particles are separated in the subsequent filtration step according to the invention by a porous membrane from the treated wastewater. This results in a filtrated wastewater with a low content of fluoride, being the permeate of the filtration step.
- the treated wastewater (permeate of the filtration step) can be further recycled by additional post-treatment steps like ion exchange, electrodialysis reversal (EDR), membrane capacitive deionization, or reverse osmosis, in order to recycle back to process or to use the treated wastewater after demineralization for other purposes as e.g. cooling tower purposes.
- additional post-treatment steps like ion exchange, electrodialysis reversal (EDR), membrane capacitive deionization, or reverse osmosis, in order to recycle back to process or to use the treated wastewater after demineralization for other purposes as e.g. cooling tower purposes.
- the inventive method is characterized by a settling step before the filtration step.
- this additional settling step at least a part of the calcium fluoride particles formed in the reaction step are allowed to settle.
- this settled part of calcium fluoride particles will mainly consist of bigger calcium fluoride particles formed during the reaction step. Due to the settling it is not necessary to bring those already settled particles to the membrane for filtration. Only smaller calcium fluoride particles which did not settle in the settling step have to be separated from the treated wastewater.
- the membrane can be chosen with a pore size adapted to the specific requirements.
- an ultrafiltration membrane with a cutoff preferably chosen from about 0.02 ⁇ m to about 0.1 ⁇ m. It is however preferred according to the invention that the membrane used is a microfiltration membrane with a cutoff chosen from about 0.1 ⁇ m to about 10 ⁇ m. Within this cutoff range values from about 0.1 ⁇ m to about 1 ⁇ m are further preferred.
- the membrane used is a ceramic membrane.
- a ceramic membrane is preferably made from aluminium oxide, titanium dioxide, zirconium dioxide or silicon carbide.
- Silicon carbide (SiC) membranes are most preferred, because they have the lowest fouling behavior, the highest permeability, and the highest chemical and physical stability. During “fouling” the outer and inner surfaces of the membrane will be covered by unwanted material (inorganic or organic or by living organisms). Ceramic membranes, in particular SiC membranes have a high resistance against such fouling. For cleaning procedures, any chemicals can be used as SiC-membranes are highly resistant against most chemicals.
- a fluoride-containing, in particular HF containing wastewater from the semiconductor industry will already have a pH value ⁇ 4, and even ⁇ 2.5. If the pH value of the wastewater to be treated is not within the necessary range of ⁇ 4, or not within the more preferred ranges, it is possible to add any acidic liquid to the wastewater prior to the reaction step. In this context it is preferred to add a mineral acid, namely hydrochloric acid, or preferably sulphuric acid or nitric acid. Any acidic wastewater can also be used.
- the inventive method it is preferred to use calcium carbonate as a powder, i.e. to add calcium carbonate to the wastewater in powder form.
- This powder preferably has an average particle size ⁇ 1 mm, wherein an average particle size of ⁇ 0.1 mm is further preferred.
- the term “average particle size” in this context refers to the so-called D90 value, defining that 90% of the particles are smaller as the corresponding value, e.g. 1 mm. In the case of calcium carbonate this D90 value can be determined by sieve analysis.
- calcium carbonate can be used in a slurry, i.e. this slurry containing calcium carbonate (normally in water) can be added to the wastewater.
- the slurry is a mixture of particulate calcium carbonate, which is insoluble in water.
- the concentration of the calcium carbonate particles in the slurry is up to 50%. Further preferred is a concentration of calcium carbonate particles in the slurry of up to 30%.
- calcium carbonate (as a powder or as a slurry) can be added quickly to the wastewater for starting and performing the reaction between calcium carbonate and the fluoride in the wastewater.
- acids other than HF e.g. hydrochloric acid or nitric acid or other acids are present in the wastewater, it could be useful to adapt the calcium carbonate dosing rate. It could even be helpful to control the pH value during calcium carbonate dosing and/or during the whole reaction step by pH measurement.
- calcium carbonate is not only the reaction/precipitation partner of the fluoride, but also acts as seed material for the growth of the calcium fluoride particles.
- the inventive method it is preferred in the inventive method to use calcium carbonate in excess to the fluoride content of the wastewater.
- the calcium carbonate/fluoride mass ratio is preferably more than 2, preferably from 2.6:1 to 5:1. In the latter range a calcium carbonate/fluoride mass ratio from 3.5:1 to 4.2:1 is further preferred.
- the excess of calcium carbonate can also depend on the fact whether phosphoric acid is present in the wastewater.
- phosphoric acid H 3 PO 4
- calcium phosphate Ca 3 (PO 4 ) 2 or apatite/hydroxyfluoroapatite (Ca 10 (PO 4 ) 6 F 2
- This calcium consumption by co-precipitation should be considered in the chosen calcium carbonate/fluoride mass ratio.
- the pH should be increased by adding any alkalinity (i.e NaOH) to pH>7.5, preferably >8.0 to fully precipitate and remove at same time the phosphates from water.
- alkalinity i.e NaOH
- the reaction time (reaction between calcium carbonate and fluoride in the reaction step) depends on the fluoride/HF content of the (feed) wastewater on the one hand, and on the desired target content of fluoride/HF in the treated wastewater on the other hand.
- the reaction time in the reaction step of the inventive method regularly will be less than 120 minutes, in particular less than 90 minutes (inventive treatment performed at room temperature, i.e. between 15° C. and 30° C., preferably under stirring/mixing).
- reaction time under mixing is from 5 minutes to 60 minutes, in particular from 20 minutes to 40 minutes.
- a most preferred embodiment of the inventive method is characterized by a reaction step in which calcium carbonate is reacted with the fluoride in the wastewater at an acidic pH ⁇ 2.5 for a reaction time between 5 minutes and 60 minutes.
- calcium carbonate particles act as a seed material for the growth of calcium fluoride particles. These particles continue to grow and form big particles which settle from the wastewater as heavy sediments.
- the (inner) core of the calcium fluoride particles remains as calcium carbonate.
- Finer and lighter (smaller) particles are also formed by the reaction and remain in the wastewater (they do not settle) or even move upwards in the wastewater.
- These lighter and smaller particles are filtered in a subsequent filtration step by a porous membrane from the treated wastewater.
- This porous membrane preferably is a ceramic membrane suited for microfiltration. It is most preferred if this ceramic membrane is made from silicon carbide (SiC).
- the present invention also comprises an apparatus for treating fluoride-containing, in particular HF-containing wastewater to remove fluoride.
- This inventive apparatus comprises at least one reaction container or reaction tank (in the following jointly designated as reaction tank) for reacting calcium carbonate at an acidic pH ⁇ 4 with fluoride in the wastewater to form calcium fluoride particles. Further, the inventive apparatus comprises at least one porous membrane, in particular at least one porous ceramic membrane for separating calcium fluoride particles from the treated wastewater in a filtration step.
- the at least one porous membrane in the inventive apparatus can be arranged in a separate filtration container or separate filtration tank (in the following jointly designation as filtration tank).
- a separate filtration container or separate filtration tank in the following jointly designation as filtration tank.
- the inventive apparatus can additionally comprise at least one separate settling container or separate setting tank (in the following jointly designated as settling tank) for settling of calcium fluoride particles.
- these calcium fluoride particles can preferably be settled before separating calcium fluoride particles from the treated wastewater by the porous membrane being part of the inventive apparatus.
- the inventive apparatus comprises a combination container or combination tank (in the following jointly designated as combination tank) both for settling of calcium fluoride particles (formed in the reaction step) and for separating calcium fluoride particles from the treated wastewater.
- a combination container or combination tank in the following jointly designated as combination tank
- inventive apparatus advantageously can additionally comprise at least one device for adding at least one acid or at least one acidic solution to the wastewater, prior to reacting calcium carbonate with fluoride in the reaction tank to form calcium fluoride particles.
- this additional device can be necessary or helpful in adjusting the pH value of the untreated (feed) wastewater.
- the membrane being part of said apparatus is a microfiltration/ultrafiltration membrane with a cutoff from about 0.021 ⁇ m to about 10 ⁇ m, preferably from about 0.1 ⁇ m to about 1 ⁇ m.
- a microfiltration/ultrafiltration membrane with a cutoff from about 0.021 ⁇ m to about 10 ⁇ m, preferably from about 0.1 ⁇ m to about 1 ⁇ m.
- the ceramic membrane being part of said apparatus is made from aluminium oxide, titanium dioxide, zirconium dioxide or silicon carbide, in particular made from silicon carbide.
- the inventive method and the inventive apparatus is associated with a number of advantages.
- the inventive combination of method steps and apparatus components results in a (CaF 2 —) sludge (retentate of the filtration step) which can be reclaimed for HF production.
- the inventive method Due to the short reaction times at room temperature in the reaction step, and due to the fact that no coagulants and other chemicals have to be used, the inventive method has a very compact footprint.
- the inventive method has low cost due to the use of calcium carbonate which is the cheapest calcium source for the formation of calcium fluoride.
- FIG. 1 An inventive apparatus which can be used for the inventive method.
- FIG. 1 shows an inventive apparatus 1 in a schematic representation.
- Apparatus 1 comprises a reaction tank 2 and a combination tank 3 , in which the settling of CaF 2 particles and the separation of CaF 2 particles from the treated wastewater can take place.
- FIG. 1 shows a supply line 4 for supplying (untreated) HF containing wastewater to the reaction tank 2 . If necessary or if appropriate acid can be supplied from a tank/device 6 to the (feed) wastewater via supply line 5 and pump 7 . The possibility to measure and control the pH value of the untreated wastewater in line 4 is also illustrated.
- CaCO 3 can be added to the wastewater in the reaction tank 2 (as a powder or a slurry) via supply line 8 and pump 9 .
- reaction tank 2 Further possible details of the reaction tank 2 are not shown. Only a stirrer 10 which can be used during the reaction step is shown as an option.
- FIG. 1 shows a supply line 11 for transferring the wastewater treated in reaction tank 2 via pump 12 into combination tank 3 . It is also illustrated that the pH value of the treated wastewater in line 11 can be measured and controlled.
- combination tank 3 in its bottom part there is a zone 13 in which CaF 2 particles can settle from the treated waste water transferred from reaction tank 2 into combination tank 3 .
- a filtration system 14 comprising at least one porous membrane 15 is shown.
- Treated wastewater containing CaF 2 particles which have not settled into the bottom part of combination tank 3 , in particular into zone 13 is filtrated through these membranes 15 via pump 17 (creating (moderate) suction pressure), resulting in a clean treated wastewater stream discharged from combination tank 3 via line 16 .
- CaF 2 particles retained from membranes 15 and CaF 2 particles already settled in combination tank 3 can be discharged from combination tank 3 via line 18 .
- the reaction time in the reaction step (under constant stirring) was set to be 30 minutes.
- the resulting batch of treated wastewater was transferred into the combination tank.
- This combination tank was equipped with SiC microfiltration membranes (cutoff 0.1 ⁇ m) with a (total) active surface of 5 dm 2 .
- the filtration was run as a submerged atmospheric filtration system wherein the permeate was drawn through the pores by using gentle suction. Bigger CaF 2 particles formed in the reaction step settled down to the bottom of the combination tank. Smaller CaF 2 particles went up and were subjected to filtration.
- the filtration capacity was set at 30 L/hour (h) with a regular backwash, namely every 10 minutes during 30 seconds under fully automatic procedure.
- the filtration performance was constant with a varying transmembrane pressure (TMP) between 250 mbar after backwash and 450 mbar before backwash.
- TMP transmembrane pressure
- Treated wastewater Fluoride content: 7 to 10 ppm
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- Engineering & Computer Science (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Hydrology & Water Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Removal Of Specific Substances (AREA)
Abstract
Description
-
- pH=2.4
- Fluoride content: 950 ppm
- Temperature: 28° C.
-
- pH: 6.5 to 7.5
- Turbidity: <0.5 NTU (Nephelometric Turbidity Unit)
- TSS (Total Suspended Solids): <1 ppm
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- 60% CaF2
- 35% CaCO3 (mainly from core of particles)
- 5% impurities
- >80% crystallinity and <20% amorphous structure.
Claims (13)
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
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EP17205716 | 2017-12-06 | ||
EP17205716.8 | 2017-12-06 | ||
EP17205716.8A EP3495327A1 (en) | 2017-12-06 | 2017-12-06 | Treatment of fluoride-containing wastewater |
PCT/IB2018/001369 WO2019111046A1 (en) | 2017-12-06 | 2018-11-30 | Treatment of fluoride-containing wastewater |
Publications (2)
Publication Number | Publication Date |
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US20200317553A1 US20200317553A1 (en) | 2020-10-08 |
US11286189B2 true US11286189B2 (en) | 2022-03-29 |
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US16/770,901 Active US11286189B2 (en) | 2017-12-06 | 2018-11-30 | Treatment of fluoride-containing wastewater |
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US (1) | US11286189B2 (en) |
EP (2) | EP3495327A1 (en) |
JP (1) | JP2021505386A (en) |
KR (1) | KR20200091445A (en) |
CN (1) | CN111836784A (en) |
IL (1) | IL275185A (en) |
SG (1) | SG11202005152SA (en) |
TW (1) | TWI785158B (en) |
WO (1) | WO2019111046A1 (en) |
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CN112573745B (en) * | 2020-11-23 | 2023-02-24 | 南京钛净流体技术有限公司 | SCR catalyst regeneration pickling wastewater treatment method |
KR102530870B1 (en) | 2022-10-14 | 2023-05-09 | 주상열 | Treatment method of waster water containing hydrofluoric acid and treatment apparatus for the same |
CN115924951B (en) * | 2022-12-21 | 2024-04-16 | 上海太洋科技有限公司 | Preparation method of calcium fluoride powder for cores |
Citations (21)
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US4171342A (en) | 1974-04-03 | 1979-10-16 | Occidental Chemical Company | Recovery of calcium fluoride from phosphate operation waste water |
US4657680A (en) | 1985-11-12 | 1987-04-14 | Amax Inc. | Wastewater treatment |
US4698163A (en) | 1985-11-12 | 1987-10-06 | Amax Inc. | Treatment of phosphate-containing wastewater |
US5043072A (en) * | 1989-10-03 | 1991-08-27 | Kurita Water Industries Ltd. | Method of treating fluoride-containing water |
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WO2019111046A4 (en) | 2019-08-15 |
WO2019111046A1 (en) | 2019-06-13 |
TWI785158B (en) | 2022-12-01 |
TW201936514A (en) | 2019-09-16 |
US20200317553A1 (en) | 2020-10-08 |
IL275185A (en) | 2020-07-30 |
KR20200091445A (en) | 2020-07-30 |
EP3495327A1 (en) | 2019-06-12 |
JP2021505386A (en) | 2021-02-18 |
CN111836784A (en) | 2020-10-27 |
WO2019111046A8 (en) | 2020-09-10 |
SG11202005152SA (en) | 2020-06-29 |
EP3962869A4 (en) | 2023-04-05 |
EP3962869A1 (en) | 2022-03-09 |
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